CN112181187A

CN112181187A - Ultrasonic induction circuit, driving method thereof and display device

Info

Publication number: CN112181187A
Application number: CN201910599313.6A
Authority: CN
Inventors: 刘英明; 王海生; 丁小梁; 王雷; 王鹏鹏; 李昌峰; 李秀锋; 张晨阳; 王天奇
Original assignee: BOE Technology Group Co Ltd
Current assignee: BOE Technology Group Co Ltd
Priority date: 2019-07-04
Filing date: 2019-07-04
Publication date: 2021-01-05
Anticipated expiration: 2039-07-04
Also published as: US20210165524A1; CN112181187B; US11537241B2; WO2021000914A1

Abstract

The embodiment of the invention discloses an ultrasonic sensing circuit, a driving method thereof and a display device. In the ultrasonic induction circuit, a first electrode of the ultrasonic sensor is electrically connected with a first end of the ultrasonic induction circuit, a second electrode is electrically connected with a second end of the first potential supply sub-circuit, and the first end of the first potential supply sub-circuit is electrically connected with a first potential supply end; the grid electrode of the M1 is electrically connected with the second electrode and the second end of the compensation sub-circuit respectively, the second pole is electrically connected with the first end of the compensation sub-circuit, and the first pole is coupled to the second potential supply end; the first terminal of the signal output sub-circuit is electrically connected to the second pole of the first transistor, and the second terminal is electrically connected to the second terminal of the ultrasonic sensing circuit. The embodiment of the invention solves the problem that the touch performance is influenced because the output value of the voltage signal for realizing the touch operation is influenced by the threshold voltage of the transistor in the sensing circuit in the conventional display equipment.

Description

Ultrasonic induction circuit, driving method thereof and display device

Technical Field

The present disclosure relates to but not limited to the field of display technologies and touch technologies, and in particular, to an ultrasonic sensing circuit, a driving method thereof, and a display device.

Background

With the development and wide application of display technology, the integration of devices with touch control functions in display devices has become the development of new display devices.

A touch device currently integrated in a display device has, for example, a fingerprint recognition function and a touch operation function, and a capacitive type or resistive type touch device is generally employed. The prior art also develops a touch device using an ultrasonic Sensor (Sensor) to realize fingerprint identification and touch operation, in the circuit of the ultrasonic Sensor with touch function, since the voltage signal output by the whole circuit of the ultrasonic Sensor is influenced by the threshold voltage (V) of the transistor on the output path of the circuit_th) The influence of (a); in addition, since the threshold voltage of the transistor on the output path is related to the manufacturing process, temperature, and other factors in the touch units (i.e., the ultrasonic sensors) configured in the display device, the threshold voltage of the transistor on the output path affects the voltage signal for implementing the touch operation, and thus, there is an error in determining the fingerprint ridge and valley, which affects the touch performance.

Disclosure of Invention

In order to solve the above technical problems, embodiments of the present invention provide an ultrasonic sensing circuit, a driving method thereof, and a display device, so as to solve the problem that in the existing display device integrated with a touch function, because an output value of a voltage signal for implementing a touch operation is affected by a threshold voltage of a transistor in a sensing circuit, a judgment of a fingerprint ridge and valley has an error, and a touch performance is affected.

An embodiment of the present invention provides an ultrasonic sensing circuit, including: an ultrasonic sensor, a first potential supply sub-circuit, a first transistor, a compensation sub-circuit, and a signal output sub-circuit;

the ultrasonic sensor comprises a first electrode, a second electrode and a piezoelectric film layer arranged between the first electrode and the second electrode, wherein the first electrode is electrically connected with a first end of the ultrasonic induction circuit, the second electrode is electrically connected with a second end of the first potential supply sub-circuit, and the first end of the first potential supply sub-circuit is electrically connected with the first potential supply end;

the grid electrode of the first transistor is respectively and electrically connected with the second electrode and the second end of the compensation sub-circuit, the second pole is electrically connected with the first end of the compensation sub-circuit, and the first stage is coupled to the second potential supply end;

the first terminal of the signal output sub-circuit is electrically connected to the second stage of the first transistor, and the second terminal is electrically connected to the second terminal of the ultrasonic sensing circuit.

Optionally, in the ultrasonic sensing circuit as described above, the first potential supply sub-circuit includes:

a second transistor having a second pole electrically connected to the second electrode, a first pole of the second transistor being electrically connected to the first potential supply terminal, and a gate being electrically connected to a switching terminal of the second transistor; alternatively, the first and second electrodes may be,

a first diode having a second pole electrically connected to the second electrode, a first pole of the first diode being electrically connected to the first potential supply terminal; alternatively, the first and second electrodes may be,

a second transistor and a first diode connected in parallel, a second pole of the second transistor and a second pole of the first diode being electrically connected to the second electrode, respectively, a first pole of the second transistor and a first pole of the first diode being electrically connected to the first potential supply terminal, respectively, and a gate of the second transistor being electrically connected to a switching terminal of the second transistor.

Optionally, in the ultrasonic sensing circuit as described above, the compensation sub-circuit includes:

a third transistor having a first pole electrically connected to the second pole of the first transistor, the second pole of the third transistor electrically connected to the gate of the first transistor, the gate electrically connected to the switch terminal of the third transistor; alternatively, the first and second electrodes may be,

a second diode having a first pole electrically connected to the second pole of the first transistor, the second pole of the second diode being electrically connected to the gate of the first transistor; alternatively, the first and second electrodes may be,

and a third transistor and a second diode connected in series, wherein a first pole of the third transistor is electrically connected to a second pole of the first transistor, a second pole of the third transistor is electrically connected to a first pole of the second diode, a second pole of the second diode is electrically connected to a gate of the first transistor, and a gate of the third transistor is electrically connected to a switching terminal of the third transistor.

Optionally, the ultrasonic sensing circuit as described above further includes:

and a power supply circuit having a second terminal electrically connected to the first electrode of the first transistor, and a first terminal electrically connected to the second potential supply terminal.

Optionally, in the ultrasonic sensing circuit as described above, the power supply circuit includes:

a fourth transistor and a fifth transistor, a second pole of the fourth transistor and a second pole of the fifth transistor being electrically connected to a first pole of the first transistor, a first pole of the fourth transistor being electrically connected to the second potential supply terminal, a gate being electrically connected to a switching terminal of the fourth transistor or the third transistor, a first pole of the fifth transistor being electrically connected to a power supply voltage terminal, and a gate being electrically connected to a switching terminal of the fifth transistor; alternatively, the first and second electrodes may be,

and a fifth transistor having a second pole electrically connected to the first pole of the first transistor, the first pole of the fifth transistor being electrically connected to the second potential supply terminal of the common port, and the gate being electrically connected to the switching terminal of the fifth transistor.

Optionally, in the ultrasonic sensing circuit as described above, the signal output sub-circuit includes:

a sixth transistor having a first pole electrically connected to the second pole of the first transistor, the second pole of the sixth transistor electrically connected to the second terminal of the ultrasonic sensing circuit, and a gate electrically connected to the switch terminal of the sixth transistor.

The embodiment of the present invention further provides a driving method of an ultrasonic sensing circuit, where the driving method is executed by using any one of the ultrasonic sensing circuits described above, and the driving method includes:

providing a first fixed potential to a second electrode of the ultrasonic sensor through a first potential supply sub-circuit;

under the first fixed potential, a preset alternating current signal is sent through the first electrode, so that the ultrasonic sensor emits ultrasonic waves;

providing a second fixed potential to the second electrode through the first transistor and the compensation sub-circuit;

the ultrasonic sensor receives ultrasonic waves returned after reaching the fingers of the user, converts the received ultrasonic waves into voltage signals and outputs the voltage signals through the signal output sub-circuit.

Alternatively, in the driving method of the ultrasonic induction circuit as described above,

the second fixed potential is the fixed potential provided by the second potential supply end minus the threshold voltage of the first transistor.

the current of the received ultrasonic converted voltage signal is:

wherein, the mu_nIs the mobility of the channel of the first transistor, C_oxIs the capacitance of the first transistor, the

Is the width-to-length ratio of the channel of the first transistor, V_GSIs the voltage between the gate and the second pole of the first transistor, the V_r2Is the second fixed potential.

Alternatively, in the driving method of the ultrasonic sensor circuit as described above, the supplying the first fixed potential to the second electrode of the ultrasonic sensor by the first potential supply sub-circuit includes:

and turning on the first potential supply sub-circuit and turning off the first transistor, the compensation sub-circuit, and the signal output sub-circuit, thereby supplying the first fixed potential to the second electrode through a first potential supply terminal electrically connected to the first potential supply sub-circuit.

Optionally, in the driving method of the ultrasonic sensing circuit, the supplying a second fixed potential to the second electrode through the first transistor and the compensation sub-circuit includes:

and turning on the first transistor and the compensation sub-circuit, and turning off the first potential supply sub-circuit and the signal output sub-circuit, thereby supplying the second fixed potential to the second electrode through a second potential supply terminal electrically connected to the first transistor.

Optionally, in the driving method of the ultrasonic sensing circuit as described above, the receiving, by the ultrasonic sensor, the ultrasonic wave returning after reaching the finger of the user includes:

through the first transistor with the compensation sub-circuit will behind the second fixed potential improves to the third fixed potential, right the ultrasonic wave of receipt is sampled, will after accomplishing the sampling the third fixed potential reduces to the fourth fixed potential, the fourth fixed potential is the static operating potential of first transistor.

Optionally, in the driving method of the ultrasonic sensing circuit, the converting the received ultrasonic wave into a voltage signal by the ultrasonic sensor and outputting the voltage signal through the signal output sub-circuit includes:

the received ultrasonic waves are converted into the voltage signals after passing through a piezoelectric film layer of the ultrasonic sensor;

and turning on the signal output sub-circuit and the first transistor, turning off the first potential supply sub-circuit and the compensation sub-circuit, and outputting a voltage signal reaching the gate of the first transistor through the first transistor and the signal output sub-circuit.

An embodiment of the present invention further provides a display device, including: the method comprises the following steps: a display panel and an array arrangement of the ultrasonic induction circuit.

Optionally, in the display device as described above, the ultrasonic sensor of the ultrasonic sensing circuit is disposed on a back plate attached to the display panel, wherein the second electrode, the piezoelectric film layer, and the first electrode are sequentially disposed on one side of the back plate away from the display panel.

The embodiment of the invention also provides a computer-readable storage medium, and the computer-readable storage medium stores executable instructions, and the executable instructions are executed by a processor to realize the driving method of the ultrasonic induction circuit.

An ultrasonic sensing circuit, a driving method thereof, and a display device according to an embodiment of the present invention are provided, in which the ultrasonic sensing circuit includes an ultrasonic sensor 110 having a first electrode, a second electrode, and a piezoelectric film layer, a first potential supply sub-circuit, an M1 and compensation sub-circuit, a signal output sub-circuit, and connection modes of the ultrasonic sensor and the sub-circuits are shown in fig. 7 to 9; when the ultrasonic sensing circuit provided by the embodiment of the invention is used for fingerprint identification or touch operation, before the ultrasonic waves which are transmitted and returned are received, a fixed potential can be provided for the second electrode through the M1 and the compensation sub-circuit, and the voltage of the fixed potential is V_r2-V_thThereby enabling the transfusionThe magnitude of the output voltage signal and the threshold voltage V of M1_thTherefore, the embodiment of the invention solves the problem that the existing display equipment integrated with the touch control function has errors in the judgment of fingerprint ridges and valleys and influences the touch control performance because the output value of the voltage signal for realizing the touch control operation is influenced by the threshold voltage of the transistor in the sensing circuit by reasonably setting the hardware structure of the ultrasonic sensing circuit.

Drawings

The accompanying drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the example serve to explain the principles of the invention and not to limit the invention.

FIG. 1 is a schematic diagram of the structure and principle of an ultrasonic generator;

FIG. 2 is a schematic diagram of the structure and principle of an ultrasonic receiver;

FIG. 3 is a schematic diagram of the structure and principle of an ultrasonic sensor;

FIG. 4 is a schematic diagram of an ultrasonic sensor and pixel structure;

FIG. 5 is a schematic diagram of a structure of a sound-transmitting induction circuit;

FIG. 6 is a schematic diagram of the ultrasonic sensing circuit shown in FIG. 5 at a voltage signal output stage;

fig. 7 is a schematic structural diagram of an ultrasonic sensing circuit according to an embodiment of the present invention;

FIG. 8 is a schematic diagram illustrating the operation of the ultrasonic sensing circuit provided in the embodiment of FIG. 7 before receiving an ultrasonic signal;

FIG. 9 is a schematic diagram illustrating the operation of the ultrasonic sensing circuit provided in the embodiment of FIG. 7 during outputting an ultrasonic signal;

FIG. 10 is a schematic structural diagram of another ultrasonic sensing circuit according to an embodiment of the present invention;

FIG. 11 is a schematic structural diagram of another ultrasonic sensing circuit according to an embodiment of the present invention;

FIG. 12 is a schematic structural diagram of another ultrasonic sensing circuit according to an embodiment of the present invention;

fig. 13 is a schematic structural diagram of another ultrasonic sensing circuit according to an embodiment of the present invention;

FIG. 14 is a schematic structural diagram of another ultrasonic sensing circuit according to an embodiment of the present invention;

FIG. 15 is a schematic structural diagram of another ultrasonic sensing circuit according to an embodiment of the present invention;

FIG. 16 is a schematic structural diagram of another ultrasonic sensing circuit according to an embodiment of the present invention;

fig. 17 is a schematic structural diagram of another ultrasonic sensing circuit according to an embodiment of the present invention;

FIG. 18 is a schematic structural diagram of another ultrasonic sensing circuit according to an embodiment of the present invention;

FIG. 19 is a schematic diagram of another ultrasonic sensing circuit according to an embodiment of the present invention;

fig. 20 is a flowchart of a driving method of an ultrasonic sensing circuit according to an embodiment of the present invention;

fig. 21 is a schematic structural diagram of a display device according to an embodiment of the invention;

fig. 22 is a schematic structural diagram of another display device according to an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that the embodiments and features of the embodiments in the present application may be arbitrarily combined with each other without conflict.

The steps illustrated in the flow charts of the figures may be performed in a computer system such as a set of computer-executable instructions. Also, while a logical order is shown in the flow diagrams, in some cases, the steps shown or described may be performed in an order different than here.

Fig. 1 is a schematic diagram of the structure and principle of an ultrasonic generator. As shown in fig. 1, the structure of the ultrasonic generator 20 may include: a Top Electrode (TE) 21 and a Bottom Electrode (BE) 22, and a piezoelectric layer 23 disposed between the Top Electrode 21 and the Bottom Electrode 22. Alternating Current (AC) voltage is input to the upper electrode 21 and the lower electrode 22, for example, the lower electrode 22 is connected to a ground terminal (GND), a fixed potential is given, AC square waves are input through the upper electrode 21, the piezoelectric layer 23 deforms, or the piezoelectric layer 23 drives the substrates of the upper and lower electrodes to vibrate together, so as to generate sound waves and transmit the sound waves; the air chamber below the ultrasonic generator 20 can be more favorable for the sound wave enhancement and better transmission. The electrode (for example, the upper electrode 21) for inputting the AC square wave in the ultrasonic generator 20 described above may be regarded as a transmission electrode (Tx).

Fig. 2 is a schematic diagram of the structure and principle of an ultrasonic receiver. As shown in fig. 2, the structure of the ultrasonic receiver 30 may also include: an upper electrode (TE)31 and a lower electrode (BE)32, and a piezoelectric layer 33 disposed between the upper electrode 31 and the lower electrode 32. The ultrasonic receiver 30 may receive ultrasonic waves emitted by other devices or apparatuses and ultrasonic waves reflected by fingers of a user after the ultrasonic waves are emitted, for example, the upper electrode 31 is a fixed electrode, the lower electrode 32 is an ultrasonic receiving electrode, when the acoustic waves reach the piezoelectric layer 33 of the ultrasonic receiver 30, the received ultrasonic waves are converted into AC voltage signals, the lower electrode 32 may be connected to the output AC voltage signals, and the voltage signals are different due to different energy reflected by ridges and valleys of the fingers. The electrode (e.g., the lower electrode 32) for outputting the voltage signal in the ultrasonic receiver 30 may be referred to as a receiving electrode (Rx).

The piezoelectric layer 23 in fig. 1 and the piezoelectric layer 33 in fig. 2 are both made of a piezoelectric material (polymer), such as a polyvinylidene fluoride (PVDF) film type piezoelectric material, and may be made of other inorganic or organic piezoelectric materials, such as aluminum nitride (AlN), lead zirconate titanate (PZT), or zinc oxide (ZnO).

Fig. 3 is a schematic diagram illustrating the structure and principle of an ultrasonic sensor. Fig. 3 is a view for combining the structures of the ultrasonic generator 20 shown in fig. 1 and the ultrasonic receiver 30 shown in fig. 2 into one device, and the ultrasonic sensor 40 illustrated in fig. 3 may include: a transmitting electrode 41, a Thin Film Transistor (TFT) substrate 42, a receiving electrode 43, a piezoelectric layer 44, a fixed electrode 45, and a touch panel 46, which are disposed in this order from a direction away from a user touch to a direction close to the user touch. The working principle of the ultrasonic sensor 40 is as follows: a transmission phase of inputting an AC voltage between the fixed electrode 45 and the transmission electrode (Tx)41, so that the piezoelectric layer 44 generates and transmits an ultrasonic wave; in the reception stage, a voltage is applied between the fixed electrode 45 and the reception electrode 43, and the received ultrasonic waves are converted into an AC voltage by the piezoelectric layer 44 and then output through the reception electrode 43. The ultrasonic waves emitted from the emitting electrode 41 reach the ridges or valleys of the user's finger, and the ridges or valleys of the user's finger have different reflection capabilities and the valleys have stronger reflected energy. Thus, the ridges or valleys are reflected by voltage signals of different intensities.

In the above description of the basic implementation principle of transmitting and receiving ultrasonic waves by taking fig. 3 as an example, the transmitting electrode (Tx)41 and the receiving electrode (Rx)43 may be fabricated on a glass substrate, that is, the receiving electrode (Rx)43 is also fabricated on the glass substrate. As shown in fig. 4, which is a schematic diagram of an ultrasonic sensor and a pixel structure, the pixel structure 50 of the display panel may include: the ultrasonic sensor comprises a TFT substrate 51, a pixel Active Area (pixel Active Area)52, a Rbias ITO53 and a Flexible Circuit board attaching module (FOG) 54, wherein Rbias represents bias voltage, Indium Tin Oxide (ITO) material can be used as the bias voltage (Rbias ITO), a receiving electrode (Rx)43 and a piezoelectric layer 44 of the ultrasonic sensor can be sequentially arranged On the pixel Active Area 52, and an emitting electrode (Tx)41 covers the piezoelectric layer 44, the Rbias ITO53 and the FOG 54. It can be seen that the transmitting electrode (Tx)41 and the receiving electrode (Rx)43 are formed on the same surface of the TFT substrate 51 in fig. 4.

The following specific embodiments of the present invention may be combined, and the same or similar concepts or processes may not be described in detail in some embodiments.

Transmitting and receiving based on the ultrasonic sensor shown in the above-mentioned fig. 1 to 4Fig. 5 is a schematic structural diagram of a sound induction circuit. The ultrasonic sensing circuit 400 shown in fig. 5 includes: an ultrasonic sensor 40, a transistor M1, a transistor M2, a transistor M3, and a diode DI1, wherein a gate G1 of M1 is electrically connected to a second electrode 43 (e.g., a receiving electrode 43) of the ultrasonic sensor 40, and a first pole D1 of M1 is electrically connected to a power supply voltage V1_CCThe second pole S1 of M1 is electrically connected to the first pole D3 of M3, the above M2 and DI1 are connected in parallel, the second poles S2 of M2 and DI1 (for example, the cathode of DI1) are respectively electrically connected to the second electrode 43, the first poles D2 of M2 and DI1 (for example, the anode of DI1) are respectively electrically connected to the fixed potential Vr, in addition, the gate G2 of M2 is electrically connected to the switch potential Vg2, the gate G3 of M3 is electrically connected to the switch potential Vg3, and the second pole S3 of M3 is the output terminal V3 of the above ultrasonic sensing circuit 400_outThe first electrode 41 of the ultrasonic sensor 40 is used to input an AC voltage signal Vac. The node Vin in fig. 5 is the potential of the second electrode 43 of the ultrasonic sensor 40.

The ultrasonic sensing circuit 400 shown in fig. 5 can be applied to a display panel, which has a structure shown in fig. 4, that is, a plurality of ultrasonic sensing circuits 40 shown in fig. 5 are configured in the display panel, and the operation process of the ultrasonic sensing circuit 400 in the display panel can be as follows:

first stage (emission stage): m2 is turned on, and a fixed potential, for example, V0, is provided to the Vin point through Vr, and at this time, all the Vin points in the pixel region of the display panel are at the fixed potential V0, that is, the potential of the second electrode 43 of the ultrasonic sensor 40; in this process, M2 may be on all the time, and Vr always gives in the signal, or M2 is off and Vr always gives in the signal, which provides the fixed potential V0 to Vin point through DI 1; when the Vin point leaks electricity, Vr can supplement a signal to the Vin point through DI1 at any time, the requirement of the phase is to ensure that the potential of the Vin point is continuously a fixed potential V0, and under the condition that the potential of the Vin point is continuously a fixed potential V0, a high-voltage square wave or sine wave is fed through the first electrode 41, so that the piezoelectric layer 44 emits an ultrasonic signal; in the ultrasonic wave transmitting stage, the second electrode 43 is a fixed potential terminal, and the first electrode 41 is a transmitting electrode (Tx);

second stage (after launch is complete): the first electrode 41 is given a fixed potential, and the potential at the Vin point is held at a fixed potential V0; since many ultrasonic waves are reflected during the process that the ultrasonic signals pass through each film layer (including the ultrasonic sensor 40 and each film layer of the display panel), these reflected signals are unwanted noise, which causes the fixed potential of the Vin point to rise from V0 to V0 ", and since there is an uncontrollable difference in V0", the potentials of different Vin points (i.e. the Vin points of different ultrasonic sensing circuits 40) in the pixel area of the display panel are different;

in view of the above-mentioned problem that the potential of different Vin points in the pixel region of the display panel before receiving the ultrasonic signal is V0 ″ and thus the potential of the Vin points is different, the problem can be solved by the following third stage;

third stage (preparation stage before reception): after the ultrasonic signal is reflected back through the film layers and the user finger interface and before the ultrasonic signal reaches the piezoelectric layer 44 again, the Vr potential terminal can provide a higher potential relative to the V0 potential, such as V1, to the Vin point through DI1, and V1> V0, at this time, the diode DI1 is turned on, and the potential of the Vin point rises to V1 due to V0 ″, so that the potential of all Vin points in the display panel can be a reference potential Vreset (i.e., V1) before the ultrasonic signal is received;

fourth stage (reception and output stage): the Vr potential terminal is pulled down again, so that the potential V1 at the Vin point is reduced to V1 ", and the V1" at different Vin points (i.e. the Vin points of different ultrasonic sensing circuits 40) in different display panels is different due to the difference of the ridges and valleys of the fingers of the user, so that the potentials of the grid G1 at different M1 in the display panels are different, and the same V is set_CCIn the case of (1), the output V of each ultrasonic sensor circuit 40 is directly determined by the potential of the gate G1 of the M1 therein_outVoltage value of (d); in the ultrasonic wave receiving stage, the first electrode 41 is a fixed potential terminal, and the second electrode 32 is a receiving electrode (Rx).

The structure of the ultrasonic sensor circuit 400 shown in fig. 5 has the following problems: the source follower of the transistor M1 may cause different threshold voltages of the transistor M1 due to the manufacturing process, temperature, and other factorsV_thIn contrast, thus, at the same V_CCIn case of (2), V of the output_outWill be influenced by the threshold voltage V of the transistor M1_thThereby causing a misjudgment of the user's finger ridge valley. The following explains the output V_outThreshold voltage V of transistor M1_thThe principle of influence. As shown in fig. 6, which is a schematic diagram of the ultrasonic sensing circuit shown in fig. 5 in the voltage signal output stage, fig. 6 shows the current direction of the output voltage signal, i.e. the output voltage signal V, by a bold dashed black line_outThe voltage value of (d) can be expressed as:

V_out＝I*R； (1)

in the formula (1), I is the current of the output voltage signal, and R is the resistance value of the rear end of the transistor M1;

in addition, in the above formula (1),

in the above formula (2), μ_nFor the mobility of the channel of transistor M1, C_oxIs the capacitance of the transistor M1,

is the width-to-length ratio of the channel of the transistor M1, which is V_GSIs the voltage between the gate G1 and the second pole S1 of the transistor M1, V_thIs the threshold voltage of transistor M1.

According to the above V_outThe calculation principle of sum I shows that V of transistor M1_thIn contrast, I is not just as large as V_GSIs also related by V_thSuch that the ridges and valleys of the user's finger are caused by different factors, thereby affecting the detection of the ultrasonic signal reflected back through the ridges and valleys.

In the ultrasonic sensing circuit 400 shown in fig. 5 and 6, the transistor M1 is V_thAnd the ridge and valley judgment of the finger of the user is wrong. In order to eliminate the above-mentioned problem of the ultrasonic sensor circuit 400, V due to the transistor M1_thThe embodiment of the present invention provides an ultrasonic sensing circuit with the following structure.

Fig. 7 is a schematic structural diagram of an ultrasonic sensing circuit according to an embodiment of the present invention. The ultrasonic sensing circuit 100 provided in this embodiment may include: the ultrasonic sensor 110, the first potential supply sub-circuit 120, the first transistor (hereinafter, denoted as: M1), the compensation sub-circuit 132, and the signal output sub-circuit 140.

In the ultrasonic sensing circuit 100 according to the embodiment of the present invention, the ultrasonic sensor 110 may include a first electrode 111, a second electrode 112, and a piezoelectric film 113 disposed between the first electrode 111 and the second electrode 112; the first electrode 111 of the ultrasonic sensor 110 and the first end P of the ultrasonic induction circuit 100_TxThe second electrode 112 is electrically connected to the second terminal 120b of the first potential supply sub-circuit 120, and the first terminal 120a of the first potential supply sub-circuit 120 is electrically connected to the first potential supply terminal P_r1. In the ultrasonic sensor circuit 100, the first terminal P of the ultrasonic sensor circuit 100_TxI.e. the signal transmitting end, can output the ultrasonic signal V at the transmitting stage of the ultrasonic sensor 110_TxFirst potential supply terminal P_r1A fixed potential V may be applied to Vin point (end of the second electrode 112) in fig. 7 during the transmitting phase of the ultrasonic sensor 110_r1。

In the ultrasonic sensing circuit 100 of the embodiment of the invention, the gate G1 of M1 is electrically connected to the second electrode 112 and the second terminal 132b of the compensation sub-circuit 132, respectively, the second pole S1 is electrically connected to the first terminal 132a of the compensation sub-circuit 132, and the first pole D1 is coupled to the second potential supply terminal P_r2(ii) a The compensation sub-circuit 132 has a unidirectional conductivity, i.e. a current can be input only from the first end 132a thereof and output from the second end 132b thereof. In the ultrasonic induction circuit 100, the second potential supply terminal P_r2Can be used as a power supply voltage terminal P_VccI.e. the second potential supply terminal P_r2Can be connected to the power supply voltage terminal P_VccAt the common port as the power supply voltage terminal P_VccCan provide a power supply voltage V under the working state of the ultrasonic induction circuit 100_CCAt the common portIs a second potential supply terminal P_r2Another fixed potential can be provided to Vin point (the second electrode 112 end) in fig. 7 after the ultrasonic sensor 110 completes transmission and during the receiving phase, and the fixed potential and the second potential supply end P_r2A fixed potential V is supplied_r2And a threshold voltage V of M1_thAnd (4) correlating.

In the ultrasonic sensing circuit 100, the second potential supply terminal P coupled to the first pole D1 of M1_r2Is connected to the power supply voltage terminal P_VccThe above description has shown that in different operation stages of the ultrasonic sensing circuit 100, the common port can implement different functions; alternatively, the two ports (i.e., the second potential supply terminal P) may be provided_r2And a supply voltage terminal P_Vcc) Split into two separate ports.

In the ultrasonic sensing circuit 100 of the embodiment of the present invention, the first terminal 140a of the signal output sub-circuit 140 is electrically connected to the second pole S1 of M1, and the second terminal 140b is electrically connected to the second terminal P of the ultrasonic sensing circuit 100_outThe second end P_outI.e. the output terminal of the ultrasonic sensing circuit 100, for outputting the ultrasonic signal V received by the ultrasonic sensor 110 and converted into the voltage signal_out。

Based on the structure of the ultrasonic sensing circuit 100 shown in fig. 7, the working process of the ultrasonic sensing circuit 100 in the embodiment of the present invention may be:

first stage (emission stage): the first potential supply sub-circuit 120 is turned on by P_r1Providing a fixed potential V to Vin point_r1And through P_TxAn AC voltage V is applied to the first electrode 111_TxThe V is_TxFor example, a high-voltage square wave or sine wave signal, i.e., transmitting ultrasonic waves; in the transmitting stage, the second electrode 112 is a fixed potential terminal, and the first electrode 111 is a transmitting electrode (Tx);

second stage (before receiving reflected ultrasound signal): the second phase is a time period after the first phase and before the ultrasonic signal is reflected from the finger of the user, M1 and the compensation sub-circuit 132 can be turned on, and since the compensation sub-circuit 132 has one-way conductivity, that is, the second phase is within the second phaseThrough the second potential supply terminal P_r2Supplied potential V_r2First through the first pole D1 and the second pole S1 of M1, and then through the compensation sub-circuit 132 to the Vin point. As shown in fig. 8, the operation principle of the ultrasonic sensing circuit provided in the embodiment shown in fig. 7 before receiving the ultrasonic signal is schematically illustrated, and the dashed line with black and thick in fig. 8 illustrates that the second potential supply terminal P is provided at this stage_r2In the process of providing the fixed potential to the Vin point, the current flows, and the common port is used as the second potential supply end P_r2And provides a fixed potential V_r2(ii) a It can be seen that the fixed potential supplied by M1 and compensation subcircuit 132 to Vin may be of magnitude V_r2-V_thAbove V_thA threshold voltage of M1, and a fixed potential V provided at this stage_r2-V_thA reference potential Vreset (i.e., V1) similar to that of the ultrasonic sensing circuit 400 shown in fig. 5 before receiving the ultrasonic wave signal; in the receiving stage of the ultrasonic wave, the first electrode 111 is a fixed potential terminal, and the second electrode 112 is a receiving electrode (Rx);

third stage (reception and ultrasound output stage): the returned ultrasonic signal reaches the piezoelectric film 113 of the ultrasonic sensor 110 and is converted into an AC voltage signal by the piezoelectric film 113, and after the reception of the ultrasonic signal is completed, the potential of the gate G1 of M1 is the AC voltage signal converted from the received ultrasonic signal, and the signal is supplied at the power supply voltage V_CCIn a fixed condition, the voltage level of the gate G1 directly affects the voltage signal V output by the ultrasonic sensing circuit 100_outAs shown in fig. 9, the operation principle of the ultrasonic sensing circuit provided for the embodiment shown in fig. 7 in the process of outputting the ultrasonic signal is schematically illustrated, and the black bold dashed line in fig. 9 illustrates the power voltage V at this stage_CCThe current of the output voltage signal flows in the stage that the common port is used as the power supply voltage end P_VccAnd provides a power supply voltage terminal V_CCIn addition, an AC voltage signal converted by the piezoelectric film layer 113 is output from a Vin point from the second electrode 112 of the ultrasonic sensor 110 to the Vin point, and the AC voltage signal at the Vin point directly affects the output voltage signal V_outThe voltage signalV_outOutput after passing through M1 and signal output sub-circuit 140.

Based on the above analysis of the operation of the ultrasonic sensing circuit 100 in the embodiment of the present invention, before receiving the returned ultrasonic signal, the reference potential V is provided to the Vin point through M1 and the compensation sub-circuit 132_r2-V_th. Therefore, the voltage signal V output by the ultrasonic sensing circuit 100_outThe AC voltage signal converted by the ultrasonic sensor 110 determines the corresponding output current:

in the above formula (3), μ_nMobility of M1 channel, C_oxIs the capacitance of M1 and,

width to length ratio, V, of M1 channel_GSIs the voltage between the gate G1 and the second pole S1 of M1, V_thIs a threshold voltage of M1, V_r2Is a second potential supply terminal P_r2To a fixed potential.

As can be seen from the above equation (3), the output voltage signal V_outAnd threshold voltage V of M1_thIrrespective, i.e. the threshold voltage V of the transistor M1 in the circuit shown in FIG. 5 is eliminated_thFor the voltage signal V output by the ultrasonic induction circuit 400_outThe influence of the touch sensing circuit 400 in fig. 5 is solved, so that the problems that the ridge and valley judgment of the user finger has errors, the touch performance is influenced, and the like are solved.

The ultrasonic sensing circuit 100 provided by the embodiment of the present invention comprises an ultrasonic sensor 110 having a first electrode 111, a second electrode 112 and a piezoelectric film 113, a first potential supply sub-circuit 120, an M1 and a compensation sub-circuit 132, a signal output sub-circuit 140, and the connection modes of the ultrasonic sensor 110 and the above sub-circuits, as illustrated in fig. 7 to fig. 9 and the above embodiments; when the ultrasonic sensing circuit 100 provided by the embodiment of the invention is used for fingerprint identification or touch operation, the ultrasonic waves which are transmitted and returned can be received before the ultrasonic waves are receivedTo provide a fixed potential with a voltage magnitude of V to the second electrode 112 through M1 and the compensation sub-circuit 132_r2-V_thSo that the magnitude of the output voltage signal is equal to the threshold voltage V of M1_thTherefore, the embodiment of the present invention, by reasonably setting the hardware structure of the ultrasonic sensing circuit 100, solves the problem that the existing display device integrated with the touch control function has errors in determining fingerprint ridges and valleys and affects the touch control performance because the output value of the voltage signal for implementing the touch control operation is affected by the threshold voltage of the transistor in the sensing circuit.

Optionally, in the ultrasonic sensing circuit 100 provided in the embodiment of the present invention, the structure of the first potential supply sub-circuit 120 may be one of the following structures.

First, the first potential supply sub-circuit 120 includes: a second transistor (hereinafter, referred to as M2) having a second pole S2 electrically connected to the second electrode 112, the first pole D2 of the M2 being electrically connected to the first potential supply terminal P_r1The gate G2 is electrically connected to the switch terminal P of M2_G2(ii) a As shown in fig. 10, which is a schematic structural diagram of another ultrasonic sensing circuit according to an embodiment of the present invention, fig. 10 illustrates a structure in which the first potential supply sub-circuit 120 includes M2.

Second, the first potential supply sub-circuit 120 includes: a first diode (hereinafter, referred to as DI1) electrically connected to the second electrode 112 at a second electrode, and a first electrode of DI1 electrically connected to the first potential supply terminal P_r1The first pole of DI1 is, for example, an anode, and the second pole is, for example, a cathode; as shown in fig. 11, in order to provide a schematic structural diagram of another ultrasonic sensing circuit according to an embodiment of the present invention, fig. 11 illustrates a structure in which the first potential supply sub-circuit 120 includes DI 1.

Third, the first potential supply sub-circuit 120 includes: m2 and DI1 connected in parallel, the second poles S2 and DI1 of M2 being electrically connected to the second electrode 112, respectively, the first poles D2 and DI1 of M2 being electrically connected to the first potential supply terminal P, respectively_r1The gate G2 of M2 is electrically connected to its switch terminal P_G2The first pole of DI1 is, for example, an anode, and the second pole is, for example, a cathode; as shown in FIG. 12, isFig. 12 illustrates a structure of the first potential supply sub-circuit 120 including M2 and DI1 connected in parallel.

It should be noted that the structure of the first potential supply sub-circuit 120 in the embodiment of the present invention is not limited to the three structures, and the structure of the first potential supply sub-circuit 120 shown in fig. 10 to 12 is taken as an example in the embodiment of the present invention, and any circuit structure that can provide a stable fixed potential to the Vin point in the transmission stage of the ultrasonic sensing circuit 100 may be used as the first potential supply sub-circuit 120 in the embodiment of the present invention.

In the ultrasonic sensing circuit 100 provided in the embodiment of the present invention, optionally, the structure of the compensation sub-circuit 132 may be one of the following structures.

First, the compensation sub-circuit 132 includes: a third transistor (hereinafter, referred to as M3) having a first pole D3 electrically connected to the second pole S1 of M1, a second pole S3 of M3 electrically connected to the gate G1 of M1, and a gate G3 electrically connected to the switch terminal P of M3_G3(ii) a Fig. 13 is a schematic structural diagram of another ultrasonic sensing circuit according to an embodiment of the present invention, in which fig. 13 illustrates a structure in which the compensation sub-circuit 132 includes M3, and fig. 13 is illustrated by way of example based on the structure of the ultrasonic sensing circuit 100 illustrated in fig. 10.

Second, the compensation sub-circuit 132 includes: a second diode (hereinafter, referred to as DI2) having a first pole electrically connected to the second pole S1 of M1, the second pole of DI2 being electrically connected to the gate G1 of M1, the first pole of DI2 being, for example, an anode, and the second pole being, for example, a cathode; fig. 14 is a schematic diagram of a structure of another ultrasonic sensing circuit according to an embodiment of the present invention, in which fig. 14 illustrates a structure in which the compensation sub-circuit 132 includes DI2, and fig. 14 is also illustrated by taking the structure of the ultrasonic sensing circuit 100 illustrated in fig. 10 as an example.

Third, the compensation sub-circuit 132 includes: m3 and DI2 connected in series, the first pole D3 of M3 being electrically connected to the second pole S1 of M1, the second pole S3 being electrically connected to the first pole of DI2, the second pole of DI2 being electrically connected to the gate G1 of M1, the gate G3 of M3 being electrically connected to its switch terminal P3_G3The first pole of DI2 is, for example, an anode, and the second pole is, for example, a cathode; as shown in fig. 15, in order to provide a structural schematic diagram of another ultrasonic sensing circuit according to an embodiment of the present invention, fig. 15 illustrates a structure in which the compensation sub-circuit 132 includes M3 and DI2 connected in series, and fig. 15 is also illustrated by way of example on the basis of the structure of the ultrasonic sensing circuit 100 shown in fig. 10.

It should be noted that the structure of the compensation sub-circuit 132 in the embodiment of the present invention is not limited to the three structures, and the embodiment of the present invention is shown by taking the structure of the compensation sub-circuit 132 shown in fig. 13 to fig. 15 as an example, and any circuit structure that can provide a stable fixed potential to the Vin point in cooperation with M1 before the ultrasonic wave is received by the ultrasonic sensing circuit 100 and the fixed potential does not affect the output voltage signal can be used as the compensation sub-circuit 132 in the embodiment of the present invention.

Optionally, fig. 16 is a schematic structural diagram of another ultrasonic sensing circuit according to an embodiment of the present invention, and on the basis of the ultrasonic sensing circuit 100 according to the foregoing embodiments, the ultrasonic sensing circuit 100 according to the embodiment of the present invention may further include:

a power supply circuit 150 having a second terminal 150b electrically connected to the first electrode of the first transistor, the first terminal 150a of the power supply circuit 150 being electrically connected to the second potential supply terminal P_r2Second potential supply terminal P shown in FIG. 16_r2Is also connected to the supply voltage terminal P_VccTo the common port of (a).

Fig. 16 is a diagram illustrating an example of the structure of the ultrasonic sensor circuit 100 shown in fig. 13, and it should be noted that, in the power supply circuit 150, the second potential supply terminal P electrically connected to the first terminal 150a thereof_r2Can be connected to the power supply voltage terminal P_VccThe common port (fig. 16 shows the structure as an example), and the common port can simultaneously supply the fixed potential V_r2And a supply voltage V_CC(ii) a In addition, the second potential supply terminal P is based on the specific structure inside the electronic circuit 150_r2And a supply voltage terminal P_VccOr two independent ports, the power supply circuit 150 of the structure can have a power supply voltage terminal P_VccAnd a third terminal 150c (shown in fig. 17 below) that is electrically connected.

The power supply circuit 150 can supply a second potential to the first terminal 150a via the second potential supply terminal P_r2(also power supply voltage terminal P)_Vcc) The whole ultrasonic induction circuit 100 is supplied with working voltage, i.e. power voltage V_CCIt is also possible to turn on M1 and the compensation sub-circuit 132 and supply a fixed potential V to the Vin point after the ultrasonic sensor 110 transmits the ultrasonic wave and before receiving the ultrasonic wave_r2-V_th。

Optionally, in the ultrasonic sensing circuit 100 provided in the embodiment of the present invention, the structure of the power supply electronic circuit 150 may be one of the following structures.

First, the power supply electronic circuit 150 may include: a fourth transistor (hereinafter, denoted as M4) and a fifth transistor (hereinafter, denoted as M5), the second pole S4 of M4 and the second pole S5 of M5 being electrically connected to the first pole D1 of M1, the first pole D4 of M4 being electrically connected to the second potential supply terminal P1_r2The gate G4 is electrically connected to the switch terminal P of M4_G4The first pole D5 of M5 is electrically connected to the supply voltage terminal P_VccThe gate G5 is electrically connected to the switch terminal P of M5_G5(ii) a Fig. 17 is a schematic structural diagram of another ultrasonic sensing circuit according to an embodiment of the present invention, in which fig. 17 illustrates a structure that the power supply circuit 150 includes the above-mentioned M4 and M5, and fig. 17 illustrates an example based on the structure of the ultrasonic sensing circuit 100 shown in fig. 16, and the embodiment shown in fig. 17 illustrates the second potential supply terminal P_r2And a supply voltage terminal P_VccTwo independently disposed ports are shown for example. It should be noted that, in the ultrasonic sensing circuit 100 according to the embodiment of the invention, if the compensation sub-circuit 132 includes M3, it is required that M4 and M3 are simultaneously turned on after the ultrasonic wave is transmitted and before the ultrasonic wave is received, and therefore, the gate G4 of M4 and the gate G3 of M3 may share one switch terminal, that is, the gate G4 of M4 may be electrically connected to the switch terminal P of M3_G3。

Second, the power supply electronic circuit 150 may include: the second pole S5 is M5 electrically connected to the first pole D1 of M1, the first pole D5 of M5 is electrically connected to the common port, which is the second potentialSupply end P_r2And a supply voltage terminal P_VccThe gate G5 is electrically connected to the switch terminal P of M5_G5(ii) a Fig. 18 is a schematic structural diagram of another ultrasonic sensing circuit according to an embodiment of the present invention, fig. 17 illustrates a structure in which the power supply circuit 150 includes the M5, and fig. 18 is illustrated by way of example based on the structure of the ultrasonic sensing circuit 100 illustrated in fig. 16.

It should be noted that the structure of the power supply circuit 150 in the embodiment of the present invention is not limited to the above two structures, and the embodiment of the present invention is illustrated by taking the structure of the power supply circuit 150 shown in fig. 17 and 18 as an example as long as it can provide the power supply voltage end P to the ultrasonic sensing circuit 100_VccIn addition, a circuit structure that provides a stable fixed potential to the Vin point before the ultrasonic sensing circuit 100 receives the ultrasonic wave and the fixed potential does not affect the output voltage signal can be implemented, and the circuit structure can be used as the power supply electronic circuit 150 in the embodiment of the present invention.

Optionally, fig. 19 is a schematic structural diagram of another ultrasonic sensing circuit according to an embodiment of the present invention. On the basis of the foregoing embodiments, in the ultrasonic sensing circuit 100 provided in the embodiment of the present invention, the signal output sub-circuit 140 may include:

a sixth transistor (hereinafter, referred to as M6) having a first pole D6 electrically connected to the second pole S1 of the M1, wherein the second pole S6 of the M6 is electrically connected to the second terminal P of the ultrasonic sensor circuit 100_outFor outputting an ultrasonic signal received by the ultrasonic sensor 110 and converted into a voltage signal, the gate G6 is connected to the switch terminal P of M6_G6(ii) a Wherein the second pole S6 of M6 is also electrically connected to the second terminal 140b of the signal output sub-circuit 140, and the second terminal 140b is also electrically connected to the second terminal P of the whole ultrasonic sensing circuit 100_out. With the signal output sub-circuit 140 configured as described above, M6 is in an off state in the phase from the transmission of the ultrasonic wave to the reception of the ultrasonic wave, and M6 may be turned on to output a voltage signal in the process of outputting the voltage signal.

Fig. 19 is illustrated based on the structure of the ultrasonic sensing circuit 100 shown in fig. 18 as an example, and M6 shown in fig. 19 only illustrates a schematic structure of the signal output sub-circuit 140, as long as a structure that the signal output sub-circuit 140 is turned off at a stage when the ultrasonic sensing circuit 100 transmits ultrasonic waves to receive ultrasonic waves and the signal output sub-circuit 140 is turned on at a stage when the ultrasonic sensing circuit 100 outputs a voltage signal can be realized.

Optionally, in the ultrasonic sensing circuit 100 provided in each of the embodiments of the present invention, the substrate may be a rigid substrate, such as a Glass (Glass) substrate, or a flexible substrate, such as a Polyimide (PI), and the M1 to M6 may be N-type Metal-Oxide-Semiconductor (NMOS) transistors or P-type Metal-Oxide-Semiconductor (PMOS) transistors. The ultrasonic sensing circuit 100 in the embodiment shown in fig. 7 to 19 is exemplified by using NMOS transistors as M1 to M6, in which case, the first electrodes of M1 to M6 are drains, the second electrodes are sources, and gates are gates, and if PMOS transistors are used as M1 to M6, the first electrodes are sources, the second electrodes are drains, and gates are gates.

Optionally, in the ultrasonic sensing circuit 100 provided by each of the above embodiments of the present invention, in order to achieve better performance, Indium Gallium Zinc Oxide (IGZO) TFTs may be used for M2 and M3, so that the leakage current of the whole circuit 100 is smaller, which may make the fixed potential at the Vin point better maintained, and facilitate the signal maintenance.

Through the structure of the ultrasonic sensing circuit 100 optimized by the above embodiment of the present invention, ultrasonic waves can be transmitted and received more efficiently, especially in the stage of receiving ultrasonic waves by the ultrasonic sensing circuit 100, the output voltage signal is more stable, and the output voltage signal is not affected by the threshold voltage V of M1 in the circuit shown in fig. 5_thInfluence.

Based on the ultrasonic sensing circuit 100 provided in the above-mentioned embodiment of the present invention, an embodiment of the present invention further provides a driving method of an ultrasonic sensing circuit, where the driving method is executed by the ultrasonic sensing circuit 100 provided in any of the above-mentioned embodiments of the present invention, as shown in fig. 20, which is a flowchart of the driving method of an ultrasonic sensing circuit provided in the embodiment of the present invention, and the driving method includes the following steps:

s610, providing a first fixed potential for a second electrode of the ultrasonic sensor through a first potential supply sub-circuit;

s620, sending a preset alternating current signal through the first electrode under the first fixed potential to enable the ultrasonic sensor to emit ultrasonic waves;

s630, providing a second fixed potential to the second electrode through the first transistor and the compensation sub-circuit;

and S640, the ultrasonic sensor receives the returned ultrasonic wave after reaching the finger of the user, converts the received ultrasonic wave into a voltage signal and outputs the voltage signal through the signal output sub-circuit.

The driving method provided by the embodiment of the present invention is executed by the ultrasonic sensing circuit 100 in any one of the implementations shown in fig. 7 to fig. 19, and the specific structure of the ultrasonic sensing circuit 100, in which the functions implemented by each sub-circuit and the electronic components have been described in detail in the above embodiments, and therefore, are not described again here.

In the driving method provided by the embodiment of the invention, steps S610 to S620 are operations performed by the ultrasonic sensing circuit 100 in a first stage (transmission stage), in which the first potential supply sub-circuit 120 is turned on through P_r1Providing a first fixed potential V to the Vin point_r1And through P_TxA preset alternating current signal, i.e. an input AC voltage signal V, is input to the first electrode 111_TxThe V is_TxFor example, a high voltage square wave or sine wave signal, to emit ultrasonic waves through the ultrasonic sensor 110; in the transmitting stage, the second electrode 112 is a fixed potential terminal, and the first electrode 111 is a transmitting electrode (Tx).

Step S630 is the operation performed by the ultrasonic sensing circuit 100 in the second phase (before receiving the reflected ultrasonic signal), which is the time period after the first phase and before the ultrasonic signal is reflected back from the user' S finger, and M1 and the compensation sub-circuit 132 can be turned on to provide the second electrode with the second fixed potential, and the second potential is provided to the terminal P_r2Supplied potential V_r2Passes through the first pole D1 and the second pole S1 of M1, passes through the compensation sub-circuit 132, and reaches Vin point, referring to the second pole D1 and the second pole S1 of M1 shown in FIG. 8A constant potential current flows, and the second constant potential can be the second potential supply terminal P_r2A fixed potential V is supplied_r2Minus the threshold voltage V of M1_thI.e. is V_r2-V_thI.e. the second fixed potential V supplied to the second electrode in step S630_r2-V_thThe reference potential Vreset (i.e., V1) is similar to that of the ultrasonic sensing circuit 400 shown in fig. 5 before receiving the ultrasonic wave signal.

Step S640 is an operation performed by the ultrasonic sensing circuit 100 in the third stage (a stage of receiving and outputting ultrasonic waves), the ultrasonic signal transmitted in S620 reaches the user' S finger and is reflected back, the returned ultrasonic signal reaches the piezoelectric film 113 of the ultrasonic sensor 110 and is converted into an AC voltage signal by the piezoelectric film 113, after the reception of the ultrasonic signal is completed, the potential of the gate G1 of M1 is the AC voltage signal converted from the received ultrasonic signal, and at the power supply voltage V, the AC voltage signal is converted from the power supply voltage V_CCIn a fixed condition, the voltage level of the gate G1 directly affects the voltage signal V output by the ultrasonic sensing circuit 100_outReferring to FIG. 9, the output voltage signal V_outTo which current flows.

Based on the ultrasonic sensing circuit 100 in the above embodiments of the present invention and the driving method of the ultrasonic sensing circuit provided in the embodiments of the present invention, before receiving the returned ultrasonic signal, the reference potential provided to the Vin point through the M1 and the compensation sub-circuit 132 is V_r2-V_th. Therefore, the voltage signal V output by the ultrasonic sensing circuit 100_outThe AC voltage signal converted by the ultrasonic sensor 110 determines the corresponding output current:

in the above formula (4), μ_nMobility of M1 channel, C_oxIs the capacitance of M1 and,

width to length ratio, V, of M1 channel_GSVoltage between the gate G1 and the second pole S1 of M1，V_thIs a threshold voltage of M1, V_r2Is a second potential supply terminal P_r2To a fixed potential.

As can be seen from the above equation (4), the output voltage signal V_outAnd threshold voltage V of M1_thIrrespective, i.e. the threshold voltage V of the transistor M1 in the circuit shown in FIG. 5 is eliminated_thFor the voltage signal V output by the ultrasonic induction circuit 400_outThe influence of the touch sensing circuit 400 in fig. 5 is solved, so that the problems that the ridge and valley judgment of the user finger has errors, the touch performance is influenced, and the like are solved.

Based on the hardware structure of the ultrasonic sensing circuit 100 provided in the above embodiments of the present invention, the first potential supply sub-circuit provides the first fixed potential V to the second electrode of the ultrasonic sensor during the phase of transmitting the ultrasonic wave_r1And at the first fixed potential V_r1Sending a preset AC signal through the first electrode causes the ultrasonic transducer to emit an ultrasonic wave, and prior to receiving the ultrasonic wave, providing a second fixed potential V to the second electrode through M1 and the compensation sub-circuit 132_r2-V_thThen, the ultrasonic sensor receives the returned sound wave after reaching the finger of the user, converts the received ultrasonic wave into a voltage signal and outputs the voltage signal through the signal output sub-circuit; when the driving method of the ultrasonic sensing circuit provided by the embodiment of the invention is used for fingerprint identification or touch operation, before the ultrasonic waves which are transmitted and returned are received, a fixed potential can be provided for the second electrode 112 through the M1 and the compensation sub-circuit 132, and the voltage of the fixed potential is V_r2-V_thSo that the magnitude of the output voltage signal is equal to the threshold voltage V of M1_thTherefore, the embodiment of the present invention reasonably sets the hardware structure of the ultrasonic sensing circuit 100 and the driving method corresponding to the hardware structure, thereby solving the problem that the existing display device integrated with the touch function has errors in determining the fingerprint ridges and valleys and affects the touch performance because the output value of the voltage signal for implementing the touch operation is affected by the threshold voltage of the transistor in the sensing circuit.

Optionally, in the driving method provided in the embodiment of the present invention, the implementation manner of S620 may include:

the first potential supply sub-circuit 120 is turned on, and the M1, the compensation sub-circuit 132 and the signal output sub-circuit 140 are turned off, so that the first potential supply terminal P electrically connected to the first potential supply sub-circuit 120 passes through_r1A first fixed potential V is supplied to the second electrode 112_r1。

Based on the structure of the ultrasonic sensor circuit 100 in the above-mentioned embodiments shown in fig. 7 to 12, in the first stage, i.e. the process of executing S610 to S620, the first potential supply sub-circuit 120 is required to be in the on state, and the M1, the compensation sub-circuit 132 and the signal output sub-circuit 140 are required to be in the off state, so that the stable first fixed potential V can be provided to the Vin point_r1。

It should be noted that, in the embodiment of the present invention, specific structures of the first potential supply sub-circuit 120 can be shown in fig. 10 to fig. 12, and types and connection manners of the electrical elements in the sub-circuit 120 have been described in detail in the above embodiment, so that no further description is provided herein.

Optionally, in the driving method provided in the embodiment of the present invention, an implementation manner of S630 may include:

the M1 and the compensation sub-circuit 132 are turned on, and the first potential supply sub-circuit 120 and the signal output sub-circuit 140 are turned off, thereby passing through the second potential supply terminal P electrically connected to the M1_r2A second fixed potential V is supplied to the second electrode 112_r2-V_th。

Based on the structure of the ultrasonic sensor circuit 100 in the above-mentioned embodiment shown in fig. 7 to 15, in the second stage, i.e. executing S630, M1 and the compensation sub-circuit 132 are required to be in the on state, and the first potential supply sub-circuit 120 and the signal output sub-circuit 140 are required to be in the off state, so that the stable second fixed potential V can be provided to the Vin point_r2-V_th。

It should be noted that, the specific structure of the compensation sub-circuit 132 according to the embodiment of the present invention can be shown in fig. 13 to fig. 15, and the types and connection manners of the electrical components in the compensation sub-circuit 132 have been described in detail in the above embodiments, and therefore are not described herein again.

Optionally, in the driving method provided in the embodiment of the present invention, the ultrasonic sensor 110 in S640 receives the ultrasonic wave returning after reaching the finger of the user, and for the receiving process of the returning ultrasonic wave, an implementation manner of the process may include:

the second fixed potential V is applied via M1 and the compensation sub-circuit 132_r2-V_thQuickly raised to a third fixed potential V_r2-V_thAfter the voltage is increased to be plus delta V, the received ultrasonic wave is sampled, and a third fixed potential V is applied after the sampling is finished_r2-V_thDecreasing the voltage of + DeltaV to a fourth fixed voltage V_r2-V_thAnd the fourth fixed potential is the static working potential of M1. The process of receiving the ultrasonic wave is a processing mode of receiving the ultrasonic wave (also called using the ultrasonic wave) by a conventional ultrasonic induction circuit.

Optionally, in the driving method provided in the embodiment of the present invention, in S640, the received ultrasonic wave is converted into a voltage signal and then output through the signal output sub-circuit, and as a process of outputting an ultrasonic wave signal, an implementation manner of the process may include the following steps:

step 1, converting received ultrasonic waves into AC voltage signals after passing through a piezoelectric film 113 of an ultrasonic sensor 110;

in step 2, the signal output sub-circuit 140 and M1 are turned on, the first potential supply sub-circuit 110 and the compensation sub-circuit 132 are turned off, and the voltage signal reaching the gate G1 of M1 is output through the M1 and the signal output sub-circuit 140.

In the embodiment of the present invention, the AC voltage signal converted by the ultrasonic sensor 110 passes through the gate G1 of M1 from the second electrode 112 to the power supply voltage V_CCIn a fixed condition, the voltage level of the gate G1 directly affects the voltage signal V output by the ultrasonic sensing circuit 100_outI.e. the output voltage signal V_outDetermined by the AC voltage signal at gate G1 of M1.

Based on the ultrasonic sensing circuit 100 provided in the above embodiment of the present invention, an embodiment of the present invention further provides a display device, as shown in fig. 21, which is a schematic structural diagram of the display device provided in the embodiment of the present invention. The display device 10 provided by the embodiment of the present invention may include: a display panel 700, and an array of ultrasonic sensing circuits 100, wherein the ultrasonic sensing circuits 100 may be the ultrasonic sensing circuits 100 in any of the embodiments shown in fig. 7 to 19.

The Display panel 700 in the embodiment of the invention may be, for example, an Organic electroluminescent Display (OLED) panel, a Liquid Crystal Display (LCD) panel, etc., in the Display device 10 shown in fig. 21, a Cover plate (CG) 710 may be covered on a light emitting side of the Display panel 700 to protect the Display panel 700, and the Display panel 700 and the ultrasonic sensing circuit 100 are attached to each other through a glue layer 720. Fig. 21 illustrates only the entire structure of the ultrasonic sensing circuit 100 arranged in an array, and does not illustrate the specific structure therein.

Optionally, fig. 22 is a schematic structural diagram of another display device provided in the embodiment of the present invention. In the display device 10 provided in the embodiment of the present invention, the ultrasonic sensors 110 of the ultrasonic sensing circuit 100 are disposed on the back plate 730 attached to the display panel 700, and one side of the substrate 730 away from the display panel 700 is sequentially disposed with the second electrodes 112 (receiving electrodes), the piezoelectric film 113, and the first electrodes 111 (transmitting electrodes) arranged in an array, where the second electrodes 112 are disposed on the substrate 110a attached to the adhesive layer 720, the ultrasonic sensors 110 of the ultrasonic sensing circuit 100 arranged in an array are illustrated in fig. 22, the ultrasonic sensors 110 of the ultrasonic sensing circuit 100 are also arranged in an array, and fig. 22 illustrates a structure in which all the ultrasonic sensors 110 share the first electrodes 111 and the second electrodes 112 are arranged in an array as an example; in addition, a protective layer 740 is disposed on a side of the first electrode 111 away from the display panel 700.

In the display device 10 provided by the embodiment of the present invention, the display panel 700 and the ultrasonic sensors 110 adopt a bonding structure, that is, the ultrasonic sensors 110 arranged in an array and the display panel 700 have the same size, which is beneficial to realize comprehensive screen fingerprint identification and touch operation. In the embodiment of the present invention, the ultrasonic sensing circuits 100 arranged in an array are integrated below the display screen (i.e., the display panel 700) of the display device 10, and the ultrasonic sensing circuits 100 are used for implementing fingerprint identification and touch operation functions in the display panel 700, and by optimizing the touch pixels (i.e., the ultrasonic sensing circuits 100) of the touch structure, when the ultrasonic sensing circuit 100 receives an ultrasonic signal, the received signal is more stable, and the performance of fingerprint identification and touch operation is higher.

The embodiment of the invention also provides a computer-readable storage medium, and the computer-readable storage medium stores executable instructions, and when the executable instructions are executed by a processor, the method for driving the ultrasonic sensing circuit provided by any one of the above embodiments of the invention can be realized. The implementation of the computer-readable storage medium provided in the embodiment of the present invention is substantially the same as the driving method of the ultrasonic sensing circuit provided in the above-mentioned embodiment of the present invention, and details thereof are not repeated herein.

Although the embodiments of the present invention have been described above, the above description is only for the convenience of understanding the present invention, and is not intended to limit the present invention. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. An ultrasonic sensing circuit, comprising: an ultrasonic sensor, a first potential supply sub-circuit, a first transistor, a compensation sub-circuit, and a signal output sub-circuit;

2. The ultrasonic sensing circuit of claim 1, wherein the first potential supply sub-circuit comprises:

3. The ultrasonic sensing circuit of claim 1, wherein the compensation sub-circuit comprises:

4. The ultrasonic sensing circuit of claim 1, further comprising:

5. The ultrasonic sensing circuit of claim 4, wherein the power supply circuit comprises:

6. The ultrasonic sensing circuit of claim 1, wherein the signal output sub-circuit comprises:

7. A driving method of an ultrasonic induction circuit, characterized in that the driving method is performed using the ultrasonic induction circuit according to any one of claims 1 to 6, the driving method comprising:

8. The driving method of an ultrasonic induction circuit according to claim 7,

9. The driving method of an ultrasonic induction circuit according to claim 8,

the current of the received ultrasonic converted voltage signal is:

10. The driving method of the ultrasonic sensor circuit according to any one of claims 7 to 9, wherein the supplying the first fixed potential to the second electrode of the ultrasonic sensor by the first potential supply sub-circuit comprises:

11. The driving method of the ultrasonic sensor circuit according to any one of claims 7 to 9, wherein the supplying the second electrode with the second fixed potential through the first transistor and the compensation sub-circuit comprises:

12. The driving method of the ultrasonic sensor circuit according to any one of claims 7 to 9, wherein the ultrasonic sensor receives the ultrasonic wave returned after reaching the finger of the user, and comprises:

13. The driving method of the ultrasonic sensing circuit according to claim 7, wherein the ultrasonic sensor converts the received ultrasonic wave into a voltage signal and outputs the voltage signal through a signal output sub-circuit, comprising:

14. A display device, comprising: a display panel, and the ultrasonic sensor circuit of any one of claims 1 to 6 arranged in an array.

15. The display device according to claim 4, wherein the ultrasonic sensor of the ultrasonic sensing circuit is disposed on a back plate attached to the display panel, and wherein the second electrode, the piezoelectric film layer and the first electrode are sequentially disposed on a side of the back plate away from the display panel.

16. A computer-readable storage medium storing executable instructions that when executed by a processor implement a method of driving an ultrasound sensing circuit according to any of claims 7 to 13.